Familiar leaching conduits, such as arch shape cross section molded plastic chambers, or stone filled trenches with perforated pipe, used for domestic and commercial wastewater systems provide interior void space, based on the thinking that a buffer space or flow equalization is thus provided for variations of inflow of wastewater. The sidewalls of conduits, where they interface with the surrounding soil, are also commonly conceived as providing surface area for percolation of wastewater, in addition to the bottom surface of the conduit. A familiar crushed stone filled trench, having a modest (4 inch) diameter perforated pipe running along its length may have about 50% void space. Currently, arch shape cross-section molded plastic leaching chambers have entirely open interiors, open bottoms and sloped and perforated sidewalls. A common cross section shape for each typical conduit has a width of about 30 to 36 inches and a height of about 12 to 18 inches. Thus this conduit may have from about 12 inches to about 18 inches of water depth at any one time. Although in reality flow goes through the sides and bottom, this patent application will assume a mostly downward flow through the bottom surface of the conduit, then the ratio of volume of water to surface area that the water will flow through is nominally in the range 12 to 1, up to 16 to 1. It has been seen that in these prior art conduits, a biomat will often form on the bottom and sides of the conduit, thereby lessening the effectiveness of the leaching conduits to properly infiltrate the wastewater into the soil. Drip irrigation lines are usually approximately one half inch in diameter and are typically buried 12 to 6 inches below grade.
Leaching conduits are typically covered with 6 to 12 inches or more of soil, for several reasons. One is to protect the conduits from damage. Another is to prevent contact of humans and animals with potentially deleterious microorganisms associated with the wastewater being treated. Still another is to prevent odors. The dimensions of the conduits discussed in the preceding paragraph would lead to the fact that the bottom surface of the conduits are typically at about 24 inches or more below the soil surface.
Generally, it is an aim to have aerobic treatment of the wastewater in the soil. Current thinking with prior art systems is that there is an air-soil gas interchange, so that oxygen is continuously supplied to the soil, to enable good microbiological treatment. However, the soil depths at which prior art conduits operate are disadvantaged in this respect. Since the bottom surface of the conduits are typically about 18 to 24 inches below the soil surface. Thus the bottom surfaces of the conduits are often in an anaerobic condition since the oxygen demand exceeds the oxygen supply. One improvement with such systems is to force air serially through the conduit and soil influence zone which surrounds the conduit, as described in U.S. Pat. No. 6,485,647 to David Potts, issued on Nov. 26, 2002, and which is incorporated by reference in its entirety.
Therefore, a wastewater system is needed that provides for greater aerobic conditions in leaching conduits, thereby allowing for greater processing of the wastewater prior and during absorption into the soil.